Red shirts' planned rally worries PM

He said he had instructed security agencies to ensure the protest did not get out of hand as he feared violence would cause damage to the country.

Meanwhile, a group of people were injured after 10 men in a pickup, hooded and dressed in black, threw stones and Home-made Bombs into a commercial building in which 300 members of the yellow shirts were celebrating the opening of a "We love the King" centre in Chiang Mai's Muang District.

As the yellow shirts fled, the men in black chased them with sticks, smashing glass doors and windows and a pickup parked in front of the building.

Kuakun Yodkam, secretary of the group "We love the King", said 10 minutes before they were attacked, he had received a phone call warning the red shirts were about to strike - but they did not believe it as they were making merit as part of the centre opening.

Pol Col Aksorn Wongyai, superintendent of Mae Ping District Police Station, vowed to bring the culprits to justice saying they had committed an outrageous offence in broad daylight before a large gathering of people.